Status: 2nd in Spanish league
Nickname: Los Merengues
THE RECORD: The nine-time European champions have been craving an historic tenth crown for the last decade and, if Jose Mourinho can satisfy that thirst in the coming season, his place among Real Madrid's all-time greats will be secure.
Not since Zinedine Zidane fired his famous winner in the 2002 final at Hampden Park have Real reigned supreme over European football and their run to last season's final four suggests this squad are not too away from ending the club's drought.
TACTICIAN: Jose Mourinho
The ever-controversial Mourinho tried to turn last season's Champions League semi-final against Barcelona into a battle to suit the combative qualities he has instilled into his Real Madrid side, yet his menacing intent was overcome by the brilliance of Pep Guardiola's side.
However, the feeling is that Mourinho has closed the chasm that existed between the big two in Spanish football last season and, if the cards fall in his favour this time, he could be the man to end Barca's dominance.
THE GAMEPLAN: So much of Mourinho's planning since his arrival at Real Madrid has been based around devising a plan to halt Barcelona, with the need to nullify the finest side on the planet crucial if this two-time Champions League winner is to continue his winning ways at the Bernabeu.
His success in stunting Lionel Messi's total dominance during his time as Inter Milan boss and, at times, with Real Madrid last season suggests he is the most likely architect of Barca's downfall. Defender Pepe can be used as a holding midfielder, while new signing Nuri Sahin is expected to add an extra dimension in the heat of battle.
MAIN MAN: Cristiano Ronaldo
Real Madrid's reliance on Ronaldo is understandable. After all, he has scored 100 goals for the club in a little over two seasons at the Bernabeu, with his winning goal in last season's Copa del Rey final banishing the notion that he goes missing in the big games.
Ronaldo's considerable ego needs to be supported by compatriot Mourinho to ensure he gets the best out of a player who is capable of bringing him glory. "This club can win the trophy everyone wants this season," Ronaldo says. "We were so close in the Champions League last time and it is only one small step forward needed now."
BIG SIGNING: Fabio Coentrao
Mourinho was keen to plug the gap that existed on the left side of his defence and he should have done just that with the £26 million capture of Portugal international Coentrao.
A fine attacking player who also boasts sound defensive qualities, his departure from Benfica has been talked about for a couple of seasons and, at the age of 23, he added a youth injection to this Real Madrid squad. "The chance to join this club is a dream beyond anything I could have expected growing up in Portugal," Coentrao says. "Now I have to prove I am good enough to play for this club."
RISING STAR: Mesut Ozil
Jose Mourinho has been keen to drag down the average age of his squad since his arrival at Real Madrid last summer and, after blooding young Germany international Mesut Ozil last season, he has taken on a similar challenge with summer signing Nuri Sahin.
A shining star in the Bundesliga with Borussia Dortmund, the challenge of playing for Real Madrid has crushed many a promising talent down the years and Sahin accepts he has much to prove in his first season with the world's most celebrated club. "My national team coach felt it was a gamble to come to Madrid, but you cannot say no to this team and certainly not to a manager like Jose Mourinho," Sahin says.
THE X FACTOR: Jose Mourinho
The Real Madrid boss would not have it any other way but to fill this role himself and there is little doubt that his confrontational, abrasive attitude will ruffle a few well-preened Champions League feathers once again this season.
His desire to take Barca out of their comfort zone, to unsettle a side who have come to expect opponents rolling over in front of them, could eventually reap rewards. While beating Pep Guardiola's men in a pure football match has proved almost impossible, Mourinho's bid to kick and frustrate them into submission may be a more suitable approach.
FLAW IN THE MAKE-UP: Jose Mourinho's determined pursuit of young Brazilian forward Neymar suggests he is concerned by the lack of cutting edge in his side as, if Ronaldo does not come up with goals in a tight game, Karim Benzema, Angel Di Maria and Gonzalo Higuain do not always save the day.
Benzema may start as Mourinho's first-choice striker this season, but the suspicion is that he would be replaced if the club allowed the coach to splash the cash on a more reliable goal source in the summer. When push and shove collide in the latter stages of the Champions League, a match-winner other than Ronaldo may need to step forward. Does Mourinho have a second game-changer against the best in Europe?
WHAT THEY SAY: "There is no doubt in my mind that the Champions League is a bigger competition than the World Cup," the always opinionated Mourinho says. "I do not need to be told that I was brought here to bring this trophy back to Real Madrid, to give them their tenth European title, and this is what we intend to do."
VERDICT: Mourinho has found a route to victory throughout his career and he could repeat that trick at Real Madrid.
Status: 3rd in Ligue 1 last season
Nicknames: OL, Les Gones ('The Kids' in local dialect)
THE RECORD: OL have participated in a dozen Champions League seasons, with their most impressive campaign coming in 2009-10 as they beat Fiorentina, Liverpool - famously winning 2-1 at Anfield - Real Madrid and Bordeaux, before losing 4-0 on aggregate to Bayern Munich in the semi-finals. They have also been quarter-finalists on three occasions: 2004, 2005 and 2006.
TACTICIAN: Remi Garde
Frustrated by three years without a domestic league title and the joyless, sterile approach of coach Claude Puel, OL president Jean-Michel Aulas opted to put the latter out of his misery during the summer, filling the vacancy with Garde, who had been working as the director of the club's academy.
At the age of 45, Garde has no experience as a head coach, but has spent most of his life in the service of Lyon, first as a midfielder and captain, recruitment advisor, assistant-coach and youth co-ordinator. A close ally of Arsene Wenger, the manager who signed him for Arsenal in 1996, Garde initially had the chance to succeed Gerard Houllier as OL first-team boss in 2008, but turned it down. He won six full caps for France and was selected for their Euro 92 squad.
THE GAMEPLAN: Remi Garde has decided on a tactical revolution at OL, calling time on the long-standing obsession with 4-3-3 and replacing it with a 4-4-2 set-up, which better suits the characteristics of the attacking-third personnel at his disposal. For the first time in three years, Lyon appear to be playing with freedom and joie de vivre and should be better to watch in the Champions League.
Key pairings are crucial to the success of this team. Brazilian winger Michel Bastos fills the left flank and Jimmy Briand takes up the role on the right; the solid defensive midfield duo of Kim Kallstrom and Maxime Gonalons are charged with repelling the opposition; with the Franco-Argentine tandem of Bafetimbi Gomis and Lisandro Lopez firing the bullets up front.
MAIN MAN: Lisandro Lopez
Bought from FC Porto two years ago for a cool €24 million, this indomitable Argentine front-man has proved to be a sound investment, scoring 15 league goals in his first season in France and 17 last term. It represents an excellent strike-rate for a player who has suffered his share of injuries and often was deployed out of position on the wing.
Since joining FC Porto from leading Argentine side Racing Club in 2005, the 28-year-old has piled up 18 goals in 43 Champions League appearances. Lopez was instrumental to Lyon's march to the semis of the 2009-10 competition, scoring seven in 12 starts.
BIG SIGNING: Bakary Kone
A promising young Burkina Faso international centre-back purchased from Third Division Guingamp, Kone was with the Breton club for four years and his proudest moment came as he helped the minnows to French Cup victory in 2009.
Rugged, speedy and quick on the turn, the 23-year-old has made huge strides technically over the past two or three seasons, but he still has a tendency to commit too many fouls and may find himself in danger of suspension in the latter stages of the Group D campaign.
RISING STAR: Maxime Gonalons
This composed and mature defensive midfielder or centre-back so nearly had his football career ended before it gathered momentum as four years ago, he fell victim to a serious foot infection. With septicaemia setting in, amputation was considered by medical experts until a cure was found and after eight months on the sidelines, Gonalons resumed his career.
Gonalons first came to European prominence in the 2009-10 season, coming off the bench to head home in Lyon's 2-1 win at Liverpool in the Champions League.
THE X FACTOR: Yoann Gourcuff
A €22 million buy from Bordeaux a year ago, this French international playmaker's first season in Lyon colours was nothing less than a nightmare, yet the feeling remains that he has genuine talent both as a creator and free-kick specialist to emerge as a key man in their Champions League challenge.
Lyon desperately need Gourcuff to rediscover the scintillating form he displayed for Bordeaux in the 2008-09 season, the campaign in which his extravagant skills were the cornerstone of the club's French League title.
FLAW IN THE MAKE UP: Looking to reduce their debt burden of around €33 million, OL have decided to forego the spend, spend, spend of recent years and concentrate on giving opportunities to home grown youngsters. However, the Champions League is an unforgiving environment and inexperienced performers tend to fail.
It remains to be seen whether Lyon can rely on the left-sided duo of full-back Aly Cissokho and winger Michel Bastos, both of whom were eager to leave this summer and could not find alternative employers. There is also concern over veteran Brazilian central defender and skipper Cris, who is clearly past his best.
WHAT THEY SAY: "I think OL can make a lot of headway this season with Lisandro and Gomis up front together," believes an upbeat ex-manager Gerard Houllier. "With Gomis as the target man and Lisandro working off him, Lyon should be very dangerous. The key will be for their team-mates to get the ball to the front men as quickly as possible. I am confident this team can do well."
VERDICT: The days when Lyon were considered contenders in Europe are gone, but they will battle it out with Ajax for second spot in Group D.
Status: Dutch champions
Nickname: De Amsterdammers
THE RECORD: Four-time European champions Ajax reigned supreme over the continent's finest for three successive years from 1971 and added an additional Champions League triumph in 1995 to enhance their proud record. Thrown into a group with Real Madrid and AC Milan in last season's Champions League, Ajax failed to threaten an appearance in the knock-out stages and they were unable to make an impact in the latter stages of the Europa League. The Dutch champions will expect to do better this time.
TACTICIAN: Frank de Boer
After Martin Jol left Ajax last December, club legend De Boer was ushered in as caretaker boss and quickly established himself as the leader of a club where he starred on the pitch for a decade from 1988. A hugely respected Dutch international with over a century of international caps to his credit, De Boer won the 1995 Champions League during his playing days at Ajax before he moved onto to star for Barcelona. This is his first permanent coaching position and his Eredivisie title triumph last season cemented his position.
THE GAMEPLAN: De Boer promotes a 4-3-3 formation and is a firm advocate of a pressing game that is based around the principle that defending starts with his attacking players. He has to prove he can achieve success in the Champions League using the free-flowing style that works against the lesser lights of Dutch football. New signings Dmitri Bulykin and Kolbeinn Sigthorsson join Siem de Jong in providing a focal point to their attack, with the support of wingers Miralem Sulejmani and Lorenzo Evecilio.
MAIN MAN: Siem de Jong
De Jong's two goals in the end of season decider against FC Twente last May went a long way to securing the Eredivisie title for Ajax and secure their place in the group stages of the Champions League, leaving his brother Luuk to lick his wounds as he was playing for Twente in that game. A product of the celebrated Ajax youth team set-up, he made his debut back in 2007 and took time to find his feet as a first team regular. Now De Jong gets his chance to confirm his worth against Europe's finest in the Champions League.
BIG SIGNING: Kolbeinn Sigthorsson
At the age of 21, this Icelandic international made a big impression with AZ Alkmaar last season and it was no surprise to see Ajax boss De Boer move to secure his services with a €4.5 million bid in July. After starting his Ajax career in sparkling scoring form, Sigthorsson is eager to prove he can take that golden touch into the Champions League. "Playing for Ajax is my dream and now I have the prospect of games against Real Madrid and Lyon in the biggest competition of them all," he says. "This is an opportunity I cannot ignore."
RISING STAR: Christian Eriksen
Ajax's tradition for unearthing brilliant young footballers looks set to be enhanced by this speedy and skilful Danish midfielder, who has already confirmed he is a top class operator at the tender age of 19. Hailed as the best young player in the Netherlands last season, there were plenty of rumours linking Eriksen with a move away from Ajax during the summer, but he is not ready to flee the Ajax nest just yet. "Clubs only talk about signing you if things are going well and my job is to make sure that continues to be my story," he says. "I am an Ajax player and feel lucky to be at this great club."
THE X FACTOR: Theo Janssen
The one-time bad-boy of Dutch football has shed his disruptive reputation and his arrival at Ajax after his summer switch from Twente confirmed he has earned the right to be respected by all in Holland. Janssen's coronation as Dutch Footballer of the Year last season was a personal highlight of a colourful career and he is convinced his new team can thrive in the Champions League. "Ajax have a tradition that is as impressive as any of our rivals in Europe," he points out. "This should convince us that we deserve to be here."
FLAW IN THE MAKE UP: The leap between what is required to win games in the Eredivisie and the Champions League often catches Ajax cold and De Boer will need to find a way of bridging that chasm if his side are to improve on last season's European disappointments. Their reliance on wide men Sulejmani and Evecilio is a concern as consistency is not the best quality of the talented duo. De Boer's tactical acumen will also be given a major test as he squares up to the likes of Real Madrid and Lyon.
WHAT THEY SAY: "We need our opponents to feel under the pressure the moment they have control of the ball and everyone can learn from the way Barcelona defend as a team," states De Boer. "This is especially important in the Champions League, where possession is so important. Finding a balance between patient football and the right level of urgency is crucial."
VERDICT: Ajax will battle it out with Lyon for second spot in Group D, but may have to settle for a New Year spot in the Europa League.
Status: Croatian champions
Nickname: Plavi (The Blues)
THE RECORD: Of their two previous Champions League appearances - 1998-99 and 1999-00 - the first was the most productive, with Dinamo finishing runners-up in their group to Olympiakos. Unfortunately for the Blues - who pulled off victories over FC Porto and Ajax that season - only the group winners qualified for the quarter-finals during those days of the competition.
Dinamo claimed their only major European trophy in 1966-67, beating Leeds United in the final of the old Fairs Cup, the forerunner of the UEFA Cup/Europa League.
TACTICIAN: Krunoslav Jurcic
This former Dinamo midfielder was brought in this summer for a second stint as head coach, taking over from the volatile Bosnian Vahid Halilhodzic, who sensationally resigned just days after leading the side to the national championship. In the 41-year-old's first spell in charge, he led them to back-to-back domestic league titles in 2009 and 2010, as well as the Croatian Cup in 2009.
Capped 21 times by Croatia, Jurcic was a member of the squad that came a most impressive third at the 1998 World Cup finals in France. He regularly started for Dinamo in their Champions League encounters in the late 1990s and early part of the new millennium.
THE GAMEPLAN: Jurcic's default formation is a 4-4-2 and, while his predecessor Halilhodzic was a defence-orientated coach and very rigid in this thinking, the new man at the helm favours a more free-flowing, enterprising style. They play a neat and measured short-passing game, with a premium on good technique and movement, but sometimes they fall into the trap of possession for possession's sake, not being incisive and speedy enough in the attacking third.
Jurcic likes to employ a midfield diamond featuring the Argentine Adrian Calello as the holder, Jerko Leko and the Brazilian Sammir in the half-back positions and Milan Badelj as the playmaker.
MAIN MAN: Milan Badelj
Dinamo look to have unearthed another gem in the shape of this 22-year-old midfield all-rounder. He often is dubbed the 'new Modric/Boban/Prosinecki' and, while he is as stylish as those Croatian greats, Badelj is also noted for his high work-rate and self-sacrifice.
Equally at home on the shoulder of the front-two, in box-to-box mode, working the right-flank or 'quarterbacking' in front of his defence, the Dinamo vice-captain can do it all. He is a graduate of the NK Zagreb academy.
BIG SIGNING: Josip Simunic
This Australian-born central defender arrived in the summer from Bundesliga outfit Hoffenheim. He has won no fewer than 86 caps for Croatia, the country of his parents' birth, but had never played in the Croatian top-flight until this season. Simunic has spent the bulk of his career in Germany, at Hamburg, Hertha Berlin and Hoffenheim.
A tall, strong and mobile defender with excellent technique, he also boasts a healthy streak of ruthlessness. Simunic was famously sent off after he received a third yellow card from English referee Graham Poll in a 2006 World Cup game against Australia.
RISING STAR: Mateo Kovacic
This extravagantly-gifted attacking midfielder is shaping up to be the next big thing in Croatian football. A fantastic dribbler brimming over with imagination and flair, Kovacic is often compared favourably in the local media to such world-class prodigies as Lionel Messi and Wayne Rooney. That may be a little over the top at this formative stage of his career, but he is certainly a fine young talent.
Born in the Austrian city of Linz to Croatian parents, he joined Dinamo in the summer of 2010 and Arsenal are one of many leading European clubs reportedly showing interest in him. Kovacic became the Croatian league's youngest-ever debutant and goal-scorer last season, hitting the target aged just 16 years and 198 days.
THE X FACTOR: Sammir
Sammir is a talented Brazilian wide midfielder and he has gone from strength to strength since joining Dinamo in 2006 from Atletico Paranaense in his homeland. Now Sammir hopes to follow in the footsteps of compatriot and fellow attacking star Eduardo, who after decamping to Dinamo, was granted Croatian citizenship.
Comfortable on either flank, creative and an assured finisher, the 24-year-old already has five Croatian league title medals in his collection, as well as extensive experience in European competition. He had to deal with plenty of media criticism last spring, though, after getting caught drink-driving.
FLAW IN THE MAKE-UP: Dinamo's midfield diamond means they are desperately short of attacking width. For all his efforts, Argentine left-back Leandro Cufre cannot do it all on his own, while right-back Sime Vrsaljko is banned for three games of this Champions League effort following his red card in the qualifiers against Malmo.
They lack firepower up front. Neither Ante Rukavina or Ivan Krstanovic, a poor man's Peter Crouch, are the answer at Champions League level, while the atmosphere at the club is not the best, with fan groups revolting over the decisions of vice-president Zdravko Mamic.
WHAT THEY SAY: "I'll tell my Lyon team-mates to beware of the trip to Zagreb," ex-Dinamo star Dejan Lovren says as he prepares to face his former club in Group D. "They are proud, well-organised and, above all, they know how to knock the ball around and be dangerous. This is a really competitive group and I expect Dinamo to come up with some fireworks."
VERDICT: Dinamo may be a powerhouse in their homeland, but the Champions League will be too much for them.